148 THYLOGENY OF FUSUS AND ITS ALLIES. 



The discovery of this species on the east African coast would go far 

 to settle this question in favor of the westward migration of the species. 

 As will be shown later, there seems to be little doubt that members of 

 another series (F. anstralis series) of somewhat closely related Fusi 

 have migrated along this path. 



Another branch of this series, that of the large and beautiful F. 

 longissinins, became widely distributed throughout the Indian ocean 

 and the Pacific Island groups. The most specialized member of this 

 branch, F. undatus, ranges from Ceylon on the west to Tahiti on the 

 east, a range covering about 130 degrees of longitude, or more than 

 one third the circumference of the globe. 



From this same stock also originated the series of heavy or compact 

 Fusi of which F. hcckii, F. laticostatiis and F. nicobaricus are typical. 

 The first of these is a rare form, having been recorded from the 

 Philippines only. Both F. nicobaricus and F. laticostatus are con- 

 fined to the Indo-Pacific region, not having been recorded from west 

 of Ceylon, or north and east of Liu Kiu (Loo Choo) off the south coast 

 of Japan. 



The members of the F. anstralis series have to all appearances de- 

 scended from some member of the F. tuberculatus series, probably 

 F. distans. F. marmoratus seems to be a direct descendant of F. 

 australis and both occupy about the same territory. They are chiefly 

 at home off the Australian coast, though they are more widely dis- 

 tributed in Indo-Pacific waters. A well-marked variety of F. mar- 

 moratus characterizes the Red Sea, but is not confined to it. This has 

 probably given rise to the variable but characteristic F. polygonoides 

 of the Red Sea, a species which has also been recorded from the East 

 Indies, 



Closely related to the Red Sea variety of F. marmoratus is F. 

 brasiliensis, the American representative of this series. This has 

 been found off the Brazilian coast, occurring as far south as Cape Frio, 

 more than twenty-one degrees south of the equator. It is also re- 

 corded from the Florida coast, and specimens doubtfully labelled as 

 coming from Suez have been identified with it. The migrations of 

 this species, or its immediate ancestor, seem to have been around the 

 Cape of Good Hope, and thence across the Atlantic. This may have 

 been simultaneous with the migration of F. distans. 



This brings us to the exclusively American F. diipetit-thouarsit 

 and its various modifications. This species, at home only on the west 

 coast of America, seems to have no immediate known Tertiary relative, 

 unless F. gabbi be considered such. Its nearest living relative among 

 the Asiatic faunas is F. novcehollandia from Australia and Tasmania. 

 The occurrence of F. dupetit-thouarsii on the west coast of America 

 suggests that its ancestors reached that coast during the Miocene sub- 



